yamaha t50c hum

Marioverkill · Post by **Marioverkill** » Tue Aug 28, 2012 10:59 am

Sorry about that Roberto!! I just changed it to public.

Mario

roberto · Post by **roberto** » Thu Aug 30, 2012 12:31 am

When this noise started? After a particular mod?

Marioverkill · Post by **Marioverkill** » Thu Aug 30, 2012 1:07 am

It was there from the beginning.I was hoping that when I worked on the amp,I would stumble across it and fix it.
Mario

Marioverkill · Post by **Marioverkill** » Sat Sep 01, 2012 11:22 pm

Any ideas Roberto?

Marioverkill · Post by **Marioverkill** » Mon Oct 29, 2012 1:07 am

Just want to bump.I know the middle of the video is a racket,overloading the camera.The first 30 seconds,you can really hear the ghost notes.Anyone ever encounter this and if so,what did you find ?

Mario

DonMoose · Post by **DonMoose** » Wed Oct 31, 2012 4:00 pm

The one mod I kept thinking about for these amps - and feared to try because the 2 I've had my hands in were already pretty hacked up - was to move the mixer stage (V3, I think) to after the tone stacks/MVs/preamp output LDRs. This would keep the late reverb recovery, but keep the reverb level and MV level controls from interfering with each other.

Of course, if you kept the early reverb recovery, this is a non-issue.

(sorry for the slight threadjack)

Marioverkill · Post by **Marioverkill** » Tue Nov 27, 2012 3:23 am

I have some waveforms for study.I show the settings of the amp in the first photo.The 2nd,is the master volume at 0.The 3rd is the master at 5.The 4th is the master at 8.The 5th is the master at 10.I am inputting 1 KHz(channel 1,top wave). The bottom wave is taken from a dummy load resistor bank consisting of (4) 2 ohm,50 watt resistors in series.I am just starting to use a scope for amp trouble shooting.Any insight would be much appreciated.

I believe the output waveform to be strange.Also,when I turn the master or gain up,notice what is happening to the input wave form.

Gentlemen,the floor is yours.

Thanks

Mario

**edit** The order of the pics are backwards.Check the tags.

Marioverkill · Post by **Marioverkill** » Wed Nov 28, 2012 1:26 am

Marioverkill · Post by **Marioverkill** » Mon May 04, 2015 3:57 am

For those who care…
I can't believe it's been this long…time sure flies…
The weird ringing noise after about 10 minutes was heat related for sure and…wait for it…it was one of the vactrols…..yee haw !!!

Mario

chopstuck · Post by **chopstuck** » Mon May 04, 2015 12:21 pm

So what's the labor charge on 3 years bench time ?

Marioverkill · Post by **Marioverkill** » Tue May 05, 2015 1:11 am

Lol!!! Good thing the customer wasn't in a hurry!!!

chopstuck · Post by **chopstuck** » Sun May 10, 2015 5:08 am

OK, I was never happy with my T50. Since you brought it up, I decided to yank it out and try again.

Well I had it fixed in about an hour. It had this terrible midrangy tone and intermittent crackles.
Pulled out both the Mid pots and the small pcb's attached to them.
Disassembled and cleaned the pots, resoldered the pots and flying leads to each board.
Reassembled and BAM! I had the sound I was looking for these past 4-5 years.
Damn, I had been looking in the wrong place all this time.

Now I get to try all the speakers I have been stockpiling!
Yeha.

Marioverkill · Post by **Marioverkill** » Sun May 10, 2015 2:25 pm

I just did a speaker swap 2 nights ago.I have the faulty vactrol jumpered while I wait for the new one. I had an eminence governor and couldn't get a goo low end.I removed it and installed an eminence Texas Heat I had.Wow! Awesome sound! Mike soldano had told me he liked this speaker.It along with the resonance(dept) control gets a big sound out of this combo.

The Amp Garage

yamaha t50c hum

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scope pics

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